Shimano caliper - micro leaks

[Al]

Thought I'd try the BB give mind and see if anyone has had any success with this:
Pretty sure another caliper has succumbed to a micro leak. Can't see anything but - Symptoms are howling brake with no power. It can be improved by cleaning the rotor and pad or burning it off on a a long down hill but deteriorates again in no time.

I've read people have resolved the issue but replacing the fluid transfer port o ring with a fractionally harder or wider one, but wouldn't know where to start sourcing such a thing. Anyone managed it?

[Bearbonesnorm]

[

I've read people have resolved the issue but replacing the fluid transfer port o ring with a fractionally harder or wider one, but wouldn't know where to start sourcing such a thing. Anyone managed it

interesting, I was always under the impression it was the piston seals that leaked. An o ring shouldn't be a problem Al, there'll be lots on-line I imagine.

[redefined_cycles]

Yes. I've suffered this too. There's one fix related to using the putoline oil instead of the shimano mineral fluid. Read somewhere in the blurb to this fluid that it's formulation helps stop it getting past seals etc etc.

Anyway, after hearing Gian mentioning it twice (or thrice) I took the jump. No more screeching, nor lever wandering. Nor heating of the calipers. Everything just works. Other day I had a few light screeches but then thwy were gone (in the pouring rain or was the ground super wet, I forget which).

Putoline fluid (let me know if you manage to convince yourself and I'll dig out a link). I bled from the bottom up too which helped clear lots of rubbish. All this gravity bleeding that the shimano reps (apparently) suggest... Load of codswallop!!

Thanks again Gian/Alpinum. Am sure he'll be here elaborating some. On that 2021 bb200 I had to walk the last few hills as the leak/screech/brake fade was so bad - it became properly unsafe...

[Boab]

My rear GRX caliper does this, absolutely no effect unless you pump the lever like a madman. Then when it finally engages, it's very week and makes an absolute racket. I was going to bleed it again and see what happened. Might just buy myself a bling Hope RX4+ FMR+20 in orange and hope it's not the lever that's knackered...

[sean_iow]

Can you mix and match Shimano and Hope? Hope use DOT fluid and Shimano use mineral oil so the seals of one may not be compatible with the fluid you choose?

[Al]

It's not a bleeding issue. The pads are getting contaminated.

I'd also always thought pistons leaking - certainly when it happened on an old set of slx that was the case. Nothing on the pistons or pad backing.

It's the o-ring that seals the connection from one half of the caliper to the other (as cheap Shimano are made in two parts) that is allegedly the culprit.

[fatbikephil]

Happened to me on two sets of calipers, third set in progress. The problem is the pistons - they are made of plastic and the sealing surface gets rougher and rougher over time. Using fork oil helps as this causes the seals to swell slightly improving sealing. But eventually this is no good either. New pistons would be the answer but so far I've failed to get them past the seals as the ones I got had no chamfer to push them in, unlike Hopes.

I generally find that once a set of pads have gotten contaminated with oil, no amount of cleaning, scrubbing, sanding or grinding will save them.....

New caliper seems to be the only option!

[Lazarus]

Can you mix and match Shimano and Hope?

no for the reasons you mention, might work for little while but its not going to work long term

[Alpinum]

Symptoms are howling brake with no power. It can be improved by cleaning the rotor and pad or burning it off on a a long down hill but deteriorates again in no time.

Indeed seems to be getting contaminated by oil from a leaking. I had this on one Shimano brake once, was a BR M775 or M665. Instead of trying to solve the problem I just got a new set of Shimano BR M7100. You can get a full set (two brakes) for about 110 quid. No idea if Plutoline 2.5 wt oil would've helped - at that time I didn't know about the Plutoline trick.

As Shaf mentioned, Plutoline HPX R2.5 solves some issues. For me it has been the wandering bite point. Lever actuation feels lighter and more responsive, brakes work better in low temps too. I don't know about any change for the quad ring seals, since I never tried to fix the leak issue I had (as mentioned above).

No idea if simply changing oil will help, but perhaps worth a try. In this case I'd let the old oil run off, remove pistons and seals, let them soak in Plutoline over night. Fiddle it together the next day, bleed the system and try again.

I generally find that once a set of pads have gotten contaminated with oil, no amount of cleaning, scrubbing, sanding or grinding will save them.....

In my experience it depends on pad material. What has worked well for me with semi metallic and sintered pads was to put the contaminated pads and rotors in stove fuel (pure benzine/white petrol) for a few minutes, rinse once in fresh petrol, let dry and use the items as if nothing happened. The petrol would still be used for the stove on winter trips.

[redefined_cycles]

I actually have the 2 calipers (SLX M7000 i think) that were contaminated/screeching and then brake-fade to not being able to stop. Over a period of a year (or maybe half) but that's what it eventually came to.

I bought a new set of m7100 which I used with standard oil for a while but levers remained the same. I have a front brake that needs swapping soon as I'll have to remove and rethread the hose through a front Travers internal fork. I'll give the old knackered caliper a shot with the fork oil Gian mentioned. Hopefully it works well, but in wither case I'll try to report back.

Bit of encouragement for me to get that new fork on!

[Cyclepeasant]

Having replaced replaced with new calipers on three of my bikes,they all have leaked again. In under 1000 miles. In fact my urban arrow cargo bike has failed in under 50 miles .
I can't believe Shimano are still denying there isn't a problem.
Replacing the o-ring halve seal???
WE SHOULD NOT BE FIXING SHIMANO'S MISTAKES!!
Brakes are an important part of any vehicle.
Can't imagine cars and motorcycles being allowed to continue having substandard components fitted.
I am losing trust in Shimano quality control/design/materials etc recently.

They are becoming too complacent.

Had another alfine hub expire recently.
The gear components just seem to be made of poor materials (remember the expression monkey metal anyone?)

Be interested to know others opinions on Shimano components.

Bit the bullet and bought another rohloff hub!
Looking at other brands of brakes as replacements.
Gonna be spendy though

AND BREATHE! Rant over...for now!

[Lazarus]

And that is why I don't own any shimano brakes
Have hope, sram, and magura and none of them have ever given me any issues ( beyond a bleed)

[redefined_cycles]

Cyclepeasant... Totally agreed. Nevwr had a problem with Avid brakes for over 10 years. Always stayed away from Shimano as the word on thw street was that they couldn't make brakes very well. Stopping power (IMO) on the cable actuated (both types) were totally rubbish compared to Avid.

Only went to Shimano recently in the past 3 years and the experience so far has been substandard. Only thing going positive for em is that the mineral oil isn't supposed to be corrosive (to skin or metals) like the Dot stuff.

Rants are good, especially when they refuse to take responsibility or at least look at the problem. I remember them first few hydraulix XTR hydraulic brakes that were reviewed poorly. You'd have thought that over 10 years on they'd have at least got their act together!!

Highly unusual!!

[redefined_cycles]

And that is why I don't own any shimano brakes
Have hope, sram, and magura and none of them have ever given me any issues ( beyond a bleed)

Well done John. I noticed Al (Speed Goat) also seemed to have done similar and gone with Magura of recently (or similar). If price wasn't a factor I'd have followed suit...

[fatbikephil]

Shimano have always had a philosophy of making things that last a few years before needing replaced by the latest and greatest. Some stuff is OK like 8-10 speed rear mechs which seemed to last for ever and XT pedals which do last forever. When the latest generation of brakes came out in 2013 they were a revelation compared to anything else - a third of the price of hopes and they worked very well. Hopes were Ok but they had plenty of problems of their own, albeit with a good warranty and spares back up. I guess other manus have caught up now and Shimano need to up their game (or use hard anodized aluminum pistons in their brakes!)

[faustus]

Can you mix and match Shimano and Hope?

no for the reasons you mention, might work for little while but its not going to work long term

Hope RX4 caliper comes in mineral or dot options so you can put them on Shimano or SRAM hydro drop levers. Mostly a flat mount option now, but they would work with Shimano MTB levers (post mount option or with adapter). But by that point may as well have a new Shimano caliper...

[whitestone]

Shimano drivetrains are really good, their brakes not so.

I originally had Shimano XT brakes on the Solaris. They lasted just over two years (the warranty period) before developing the mico-leak problem. Persisted for a year or so then replaced with Hopes which, apart from replacing the pads when worn, have needed zero maintenance in six+ years.

Back when I got the bike the price difference between the XTs and Hopes was massive, things are much closer now. The only real downside to Hopes is that they are somewhat "agricultural" in design and the angular nature of the oil reservoir is less than comfortable on multi-day rides so you "lose" a hand position.

[Boab]

Can you mix and match Shimano and Hope? Hope use DOT fluid and Shimano use mineral oil so the seals of one may not be compatible with the fluid you choose?

They do the RX4+ calipers in both DOT and MIN flavours...

Edit: I see faustus beat me to it...

[Cheeky Monkey]

SRAM brakes

Not touched them since the godawful Codes (IIRC). Only brakes that ever failed on me when riding.

I just stick to Hope. They work and you can work on them

[faustus]

Had some Elixir R brakes back in the day - total crap, that was the last sram brake for me. Not had too many issues with Shimano (good old M755s didn't leak!) but Magura often looks a decent alternative, maybe not stonking power, but reportedly reliable at least?

[Lazarus]

Hope RX4 caliper comes in mineral or dot options so you can put them on

Cheers and news to me

My sram brakes ( code perhaps and rival on drop bar) have been faultless. Road seen 5000 miles without a bleed ( and were second hand) mtb at 2000 miles , from new, with a pad change

[Jurassic]

I've had multiple sets of Shimano brakes and never had a problem with this until recently. I used to read these threads and wonder what people were doing wrong with their Shimano brakes. All that changed with my most recent bike acquisition (a Giant Reign E+1). It came with Shimano XT 4 pot brakes (which I've used and loved on multiple other bikes). The front brake was problematic from day one. I bled it countless times, changed pads, even went up to a 220mm rotor and still I had a squeeling brake with no initial bite, not much power and wandering bite point. Eventually I admitted defeat and started looking at Hope brakes as a potential replacement/upgrade but I'd read about people grafting Magura calipers onto Shimano levers with great success. I managed to find a new Magura MT5 brake quite cheap and went for it. The conversion is easy, just chop off the nasty plastic Magura lever, fit a new barb and olive (either Shimano or Magura works, I used Shimano), bolt it together and after a quick bleed (again Shimano or Magura fluid works, you can even mix them apparently) off you go. The result is amazing, the most powerful, consistent brakes that I've ever used. I was so impressed I did the rear one as well (even though the OE Shimano brake had been working fine). You get the lovely Shimano levers with non of the inconsistency that Shimano brakes are notorious for and it's a relatively cheap modification.